Since it is quiet here, I'll give you an update on my pineapple!
I posted the blossom two months ago, it has turned into a proper fruit. I expect it to grow twice this size before harvest. On the left you can see the dried-out stem of the first fruit. The new stem branched off sideways. I have squeezed in a stone from below to keep it upright. The fruit will soon need support from above, or risk toppling.
The leaves are a bit of a hazard, sharp and pointy as the fruit crown. I'm cutting the tips before they reach eye-level.
Growing next to the pineapple is a young cotton plant (hopeful) and the top of an avocado (dying).
You may be right that I don't use enough fertilizer, I usually do a bit in summer but I haven't used any during the last 8 months. And I don't know what the brown stripes on the leaves are about, but it doesn't seem to stop the growth.
But I know that the leaves also produce some white waxy substance on the underside, which is probably what you're seeing. It can be rubbed off. (Or at least I hope this is what I just rubbed off, lol.) The Pineapple manual (PDF) says it is to protect from moisture loss.
I know they're sort of waxy, and I know I haven't grown pineapples (or ananas as we say in the rest of languages), but I googled a bunch of photos to make sure what I was seeing is the hue slightly being pale.
Idk if I have a knack for that, I at least remember reading research that green-red deficient ppl, such as I, can sometimes perceive more shades of green and brown, but that's beside the point as am going mostly from my home gardening experience.
I've grown weed and then basils and other herbs and cacti and whatnot and it all sort of applies even though not all plants need to be the same hue obviously. But the first sign of a plant being "hungry" is often — to me — anything green being a bit too pale.
But since this isn't like massive deficiency anyhow, it's alright. But I would perhaps consider doing mild fert solutions every second or even everytime you water, depending on how much it drinks (that's a whole other thing which I can't know from here).
You can buy both needed ferts from a supermarket. Just get one that's "basic" and usually green bottles or smth, just basic plant food, they're for the growth phases of most any plants. Then also look if you can find one for orchids/blooming, they're sometimes purple. (I think you said Austria perhaps and I'm EU as well but idk if the colours are some national level thing.)
In the first one or maybe even two fertilisations I'd mix them half and half with half of a low-side of the recommended amount. So that together they equal about the normal amount but sort of mixed.
Going into details here but in plant food bottles you'll see NPK numbers, standing for Nitrogen Phosphorus and Potassium (K is Kalium, how many other countries and Latin says potassium). And "growth" plant food will have a number something like 20-5-5 and bloom something like 5-15-10. Although there are balanced ones with like 10-10-10, you could use one of those for the first one or two times and then when the pineapple gets bigger (how long does it take to grow idk) start putting more a bloom type, high in phosphorus, because the plant is then making the fruit and that requires phosphorus and and that point it's just using thw energy in the leaves, not growing more, for which it would need the nitrogen.
Just take care not to overdo it. Which is easier said than done I guess. But I think looking into and using them a bit would definitely help your future harvest a bit.